DATA SET: Microphysical Measurement Package (MMP) 1. GENERAL INFORMATION The MMP data set is part of the atmospheric measurements collected in the intensive observation period of the Tropical Ocean Global Atmosphere- Coupled Ocean Atmosphere Response Experiment (TOGA-COARE). Andy Heymsfield of NCAR is the Principal Investigator and the data set is archived at the Goddard DAAC. TOGA-COARE is an international research program aimed at investigating the interactions between the atmosphere and ocean in the warm pool region of the Western Pacific, a region roughly bounded by the latitudes 30N and 30S and the longitudes 140E and 160E. The field experiment phase of the program took place from November, 1992 through February, 1993. The field experiment involved the deployment of research vessels and buoys, ship- and land-based Doppler radars, multiple low- and high- level aircraft equipped with many different types of airborne sensors, as well as a variety of surface based instruments. MMP was part of the NASA TOGA-COARE campaign. The NASA component, while contributing to the overall COARE objectives, emphasized the scientific objectives associated with the Tropical Rainfall Measuring Mission (TRMM) and NASA's cloud and radiation research programs. 2. INSTRUMENT INFORMATION 2.1 Instrument Mission and Objectives The MMP consisted of four instruments installed and operated by NCAR aboard the NASA DC-8. Each instrument is listed here with the data parameters it provides. Six parameters are derived from the instrument measurements; the seventh parameter, vertical velocity, is calculated using data from the NASA DC-8 DADS: NCAR temperature probe: o Ambient temperature in degrees Celsius o Calibrated total temperature in degrees Celsius NCAR Cryogenic frost point hygrometer: o Calibrated cryogenic dew point temperature in degrees Celsius o Calibrated cryogenic frost point temperature in degrees Celsius Rosemont ice accretion probe: o change in voltage over change in time (dV/dt) in millivolts per second (mV/s) Lyman-Alpha sensor: o Raw voltage output of the sensor in volts Calculated from DC-8 DADS data: o Vertical velocity in meters per second 2.2 Instrument measurements and parameters Following are the data parameters from the MMP data set as listed in the header of each data file. The prefix "NCAR" on the second through the fourth parameters is to distinguish them from their counterparts acquired by the DC-8 DADS. Time(hrmnsc) - UTC time - acquired from the DC-8 DADS NCAR Ambient Temp(C) - The calibrated ambient temperature from NCAR's temperature probe 102AU1AF, serial number 41716, in degrees Celsius. The sensor was post flight calibrated from 40 to -45 degrees C with a linear curve fit in the NCAR/RAF Calibration laboratory to + or - 0.1 degrees C. A recovery factor was determined from aircraft maneuvers that were performed on flight number 18. The heating effects of the de-icing probe were also corrected for. The NASA DADS data mach number and pressure value were used to calculate the NCAR Ambient Temperature. This value at worst case is + or - 1 degrees Celsius. NCAR Total Temp(C) - The calibrated total temperature from NCAR's temperature probe. Same comments as above for ambient temp. NCAR Dew Pt(C) - The calibrated cryogenic dew point temperature from NCAR's cryogenic frost point hygrometer unit #1 in degrees Celsius. The mirror temperature was pre flight calibrated from -15 to -80 degrees C in the NCAR/RAF Calibration laboratory to an absolute value of + or - 0.3 degrees C. The inlet pressure was calibrated to + or - .6 millibars. The NASA DADS data pressure value and the NCAR ambient temperature were used with the cryo mirror temperature and cryo inlet pressure to calculate the Dew point temperature, which should have a value close to + or - 1.5 degrees C. An offset of -4.2 degrees C should be corrected for when you use this dew pt data. You should contact the PI about this parameter to find out the latest information. NCAR Frost Pt(C) - The calibrated cryogenic frost point temperature from NCAR's cryogenic frost point hygrometer. Same comments as above for dew pt. Icing Probe(dV/dt)(mV/s) - The change in voltage over change in time of the Rosemount 871F ice-accretion probe in millivolts per second. The data was recorded with 5 mV/s resolution and the instrument can bounce with about 10 mV/s of noise when nothing is present so we recommend that a value of at least 15 mV/s for a 2 or 3 second time period be used as a detection threshold for liquid water. Lyman Alpha(Volt) - The raw voltage output of the Lyman-alpha sensor. NCAR Vertical Velocity Calculation(m/s) - The calculated vertical air velocity in meters per second. The vertical velocity was calculated using a method used in the past by NCAR. The method uses such things as coefficient of lift at zero angle of attack, the take-off weight of the aircraft, the burn rate, the density, the true airspeed, etc . Since the aircraft's weight and burn rate had to be estimated (from NASA), the vertical velocities are offset for each flight(usually about -2 to -6 m/s). This offset sometimes changes during the flight if the burn rate estimate differs greatly from the actual burn rate. These offsets can be corrected by simply adding the average offset for the appropriate time period. This calculation loses accuracy when the plane has a roll of greater than about +/-3 degrees, therefore a dummy value of 99999 is placed in the data set when that occurs. The vertical velocity calculation is also averaged over a 9 second period, because of the characteristic response time of the calculations. The investigators have not yet fully analyzed the values, but are confident that they give a very good qualitative estimate, and a good quantitative estimate of the vertical air velocities. 3. DATA ORGANIZATION 3.1 General Description The MMP data is about 26 MB in total volume with a typical file size of about 2.2 MB. It consists of 12 ascii files named "mmparchive.fnXX", where XX is a 2 digit flight number. The MMP produced data on 12 of the 13 mission flights made by the NASA DC-8 during the TOGA COARE campaign. The following table relates MMP data files to ER-2 and DC-8 flight numbers and dates for the 13 mission flights of the NASA/TOGA COARE campaign. The objectives column (Obj) is included for the convenience of the user; the mission objective defaulted to Radiation (Rad) unless convection (Con) was forecast in the target area. Date(UTC) ER-2 Flight DC-8 Flight MMP File Obj --------------------------------------------------------------------- Jan 11-12 93-053 93-01-06 Rad Jan 17-18 93-054 93-01-07 mmparchive2.fn07 Con Jan 18-19 93-055 93-01-08 mmparchive2.fn08 Con Jan 25-26 93-056 93-01-09 mmparchive2.fn09 Rad jan 31-Feb 1 93-057 93-01-10 mmparchive2.fn10 Rad Feb 4 93-060 93-01-11 mmparchive2.fn11 Con Feb 6 93-01-12 mmparchive2.fn12 Con Feb 7 93-061 Feb 8-9 93-062 93-01-13 mmparchive2.fn13 Con Feb 10-11 93-063 93-01-14 mmparchive2.fn14 Con Feb 17-18 93-01-15 mmparchive2.fn15 Con Feb 20-21 93-065 93-01-16 mmparchive2.fn16 Con Feb 22-23 93-066 93-01-17 mmparchive2.fn17 Con Feb 23-24 93-067 93-01-18 mmparchive2.fn18 Rad 3.2 Data format Each MMP data file begins with a file header followed by the data in tabular format. An example of the file contents is shown below: TOGA COARE DC-8 Flight 93-01-07 format (i6,7f11.4) Time(hrmnsc), NCAR Ambient Temp(C), NCAR Total Temp(C), NCAR Dew Pt(C), NCAR Frost Pt(C), Icing Probe(dV/dt)(mV/s), Lyman Alpha(Volt), NCAR Vertical Velocity Calculation(m/s) 231010 -63.5556 -50.6920 99999.0000 99999.0000 0.0000 -2.0560 -1.8840 231011 -63.5556 -50.6920 99999.0000 99999.0000 0.0000 -2.0900 -2.6133 231012 -63.5988 -50.6920 99999.0000 99999.0000 0.0000 -2.0850 -3.3396 231013 -63.5988 -50.6920 99999.0000 99999.0000 0.0000 -2.0950 -4.0531 231014 -63.6421 -50.6920 99999.0000 99999.0000 0.0000 -2.0460 -4.7766 231015 -63.7371 -50.7929 99999.0000 99999.0000 -4.8830 -2.0220 -6.3676 231016 -63.6855 -50.6920 99999.0000 99999.0000 0.0000 -2.0310 -6.3727 231017 -63.7289 -50.6920 99999.0000 99999.0000 4.8830 -2.0170 -6.4841 231018 -63.7289 -50.6920 99999.0000 99999.0000 -4.8830 -2.0310 -6.6852 4. DATA ACCESS 4.1 FTP access to MMP data The MMP data set is currently available via FTP from the Goddard DAAC, and may be retrieved by following the procedure below: o ftp daac.gsfc.nasa.gov o login - anonymous o password - your Internet address o cd pub/toga_coare/aircraft/nasa_dc8/mmp If the data file ends in the extension "Z", it has been compressed with the UNIX utility "compress" and may be decompressed, on a UNIX system, as follows: uncompress mmp.tar.Z If the file contains ".tar", it is a composite file created by the UNIX utility tar and may be handled as follows: To list the files in the tar file: tar tvf mmp.tar To extract an individual file(s) from the tar file: tar xvf mmp.tar To extract all files from a tar file: tar xvf mmp.tar If you are not on a UNIX system, contact TOGA-COARE user support to have the data files extracted at the archive. You may then retrieve them using FTP's "mget" (for multiple files--wild cards allowed) or "get" command: mget mmp* 4.2 Tape access to MMP data If you wish to order the MMP data on tape, please contact TOGA COARE user support (see Section 6, Points of Contact). Data are available on 4 mm (DAT), high or low density 8 mm (Exabyte), and 6250 Bpi 9-track tapes. Tapes are created with UNIX utilities "dd" and "tar" on a Silicon Graphics 440 system. The no-swap device and a block size of 63.5 KB (i.e., blocking factor of 127) are used. Tapes may be requested in "dd" or "tar" file format. By default the data are archived and distributed incompressed format; however, they are available in uncompressed format by special request. Each tape distributed by the Goddard DAAC contains printed paper labels with the names of the files it contains in the order they were written. Files are compressed using the standard UNIX "compress", indicated by a ".Z" appended to the data file name, and should be uncompressed using the UNIX "uncompress" command. The same utility that was used to create the tape, "dd" or "tar", must be used to access the data. If compressed files are requested, the data are compressed before the "dd" or "tar" utility is executed. Therefore, compressed data should be uncompressed after copying it from tape to local disk. To read a "tar" format tape on a computer with a UNIX operating system, use the command: tar xvfb 127 where xvbf are tar command key arguments: x indicates that the data are to be read from tape v requests verbose output, i.e., processed file names will be listed b states that a blocking factor is specified f states that an archive name is specified 127 is the blocking factor The fields in < > are system specific and may specify a device such as a tape drive, or it may specify a file directory, etc. The specific parameters are dependent upon your local workstation configuration (e.g., this will be /dev/8mm1nr if you were to read the tape off the 8mm1 tape drive on the DAAC computer and the nr specifies the no rewind option). To read a tar format tape on a VAX computer with a VMS operating system, you will need vmstar public domain software. Use the command: mount /FOREIGN/RECORD=512/BLOCK=10240 vmstar xvf =20 Note that the tape should be written with a blocking factor of 20 in order to translate to a block size of 10 KB that vmstar can read. As mentioned above, the default block size used by the DAAC in writing data to tape is 63.5 KB. Therefore, please notify the DAAC if a tape is going to be read with a VAX VMS workstation. To read a "dd" format tape on a computer with a UNIX operating system, use the command: dd if= of= bs=65024 where: if= specifies the tape drive with "no rewind option" of= specifies the desired output file name bs=65024 indicates the block size in bytes=20 To read "dd" format tapes on a VAX computer with a VMS operating system, use the "copy" command. A public domain software, lzw, is available to read UNIX compressed data format on VAX VMS. To read compressed data files, you must first use "vmstar" or the "copy" command to unload the data from tape. Then issue the "lzw" command. 5. QUALITY ASSESSMENT 5.1 Times UTC times were acquired from the DC-8 DADS. 5.2. Data quality factors Factors to be considered in assigning a quality value to the output from each instrument are discussed in Section 2.2 above. 5.3 Bad or missing data values The value 99999.0000 is used to designate missing or bad data (i.e., when vertical air velocity calculations went bad because of aircraft roll). 6. POINTS OF CONTACT For NASA/TOGA COARE user support, please contact: Pat Hrubiak EOS Distributed Active Archive Center(DAAC) Code 902.2 NASA Goddard Space Flight Center Greenbelt, Maryland 20771 Internet: hrubiak@daac.gsfc.nasa.gov (301) 286-1381 (voice) (301) 286-1775 (FAX) For information about the scientific content and quality assurance of MMP data, contact: Principal Investigator: Andy Heymsfield NCAR/MMM PO Box 3000 Boulder, Colorado 80307 heyms1@ncar.ucar.edu (303) 497-8943 (voice) (303) 497-8181 (FAX) For data processing information on MMP, contact: Greg Melvin NCAR/MMM melvin@oak.mmm.ucar.edu (303) 497-8947 (voice) 7. DATA STATUS/PLAN The MMP data first became available on DAAC public FTP in May of 1993. Please see other subdirectories of the FTP directory "toga-coare" for other TOGA-COARE data sets. After a 12 month validation period, data will gradually be removed from the public FTP area and become part of Goddard DAAC's main archive. Users can access then the main archive through the DAAC Information Management System (IMS), a menu-driven user interface with online tutorials: telnet daac.gsfc.nasa.gov login: daacims password: gsfcdaac 8. REFERENCES Science Data Workshop - II, Albuquerque, New Mexico, March 15-17, 1994, Workshop Proceedings.